The German weather service forecasts temperatures of 12 to 13 degrees Celsius for Thursday and Friday, locally up to almost 20 degrees at the turn of the year and 16 and 17 degrees on New Year’s Day. “It will be the warmest turn of the year since weather records began in 1879, since the Bavarian Weather Service was established,” says climatologist Lothar Bock.
SZ: Cold snap with snow in mid-December and almost spring-like temperatures on New Year’s Eve. How can this abrupt change from freezing cold to mild temperatures be explained?
Lothar Bock: Our climate is basically determined by general weather conditions. At the boundary between polar and subtropical air, the so-called polar front, low-pressure areas form, behind which cold air flows. In December, the polar front zone passed relatively far south over Europe. In mid-December, a strong low developed over the North Atlantic. That moved further towards Iceland and remained stationary, as we say, and so the general weather situation changed relatively quickly to a south-west situation. The Icelandic low now pushes warm air from Africa towards Bavaria and the Alps and expels the cold to the north and north-east.
Lothar Bock is a meteorologist and climatologist at the German Weather Service.
(Photo: Diana Babic)
Is that already a noticeable effect of climate change?
That’s a good question. As far as the general weather conditions are concerned, it is difficult to say. There are years when more high or low pressure regimes prevail. However, the rise in temperature is very clear. It has warmed by 1.5 to two degrees since the end of the 19th century. This clearly points to a change.
Will a foehn, i.e. the warm fall wind that is known for the Alps and Munich, also be expected in the next few days?
Foehn effects can always occur in south-west weather conditions.
The sudden mildness and warmth in the middle of winter: will it only be limited to southern Bavaria?
No, the mild air will even affect large parts of our continent, with the exception of Northwest and Northern Europe.
Does the extreme cold snap in parts of the USA also play a role in the weather phenomenon in Germany?
In the moment not. There is an old rule of thumb that dates back to the days before computers and forecasting programs existed. This says that after about two weeks you can feel a change in the weather in some form here and in Europe. However, it is more the case that a La Niña phenomenon can be observed over the Pacific. And in contrast to El Niño, this tends to mean low-precipitation and mild winters in Europe. In this respect, the probability of a major cold snap here is rather low.
Can we still expect snow this winter?
Unfortunately things are looking bad at least until mid-January.